1. Field of the Invention
The present invention relates generally to hybrid vehicles and particularly to hybrid vehicles employing a motor together with an engine.
2. Description of the Background Art
In recent years, electric vehicles, hybrid vehicles employing a motor together with an engine, and other similar vehicles considering environmental issues are increasingly gaining attention.
Japanese Patent Laying-Open No. 09-098514 discloses a vehicular power supply device mounted in a hybrid vehicle.
This vehicular power supply device can regenerate electrical energy from energy generated by braking a vehicle that is mainly or supplementarily driven by a motor. The vehicular power supply device has a power-feeding-and-charging circuit configured by a capacitor of large capacitance and a battery connected parallel to the motor, and a breaker allowing the capacitor and the battery to be independently connectable/disconnectable to the motor.
Therefore, even in a state of running in which acceleration and deceleration are repeated frequently, it is possible to sufficiently charge the capacitor of large capacitance to be ready for subsequent acceleration, and efficiency of energy regeneration can be improved.
The vehicular power supply device as disclosed in Japanese Patent Laying-Open No. 09-098514, however, has the following disadvantage: If the capacitor is insufficiently charged, an insufficient torque is caused, resulting in poor feel of acceleration. More specifically, if the capacitor is fully charged, optimum acceleration is provided. If the capacitor is insufficiently charged, however, the vehicle cannot provide a continuously increasing output, and hence cannot provide lasting acceleration. For sports type vehicles, in particular, it is desirable that smooth acceleration can be felt even if the capacitor is insufficiently charged.